The vast majority of premeditated murders are not done by someone who just wants to kill, and so looks for someone to kill that will be more morally defensible. They are done by people who really want to kill a particular person or group who they hate, or view as a threat. Serial killers are also generally not doing the Dexter thing. They have their own targetting preferences that aren’t usually aligned with social morality.

So, no. Probably no one ever has done that.